A Scalable ID-based Constant-round AGKE Protocol with Logarithmic Computation Complexity

Group key establishment is one of the basic building blocks in securing group communication. In this paper, motivated by Desmedt's BD-II protocol, we propose a secure ID-Based group key establishment protocol which has a constant number of rounds and requires only (log ) O n computation and communication. Our scheme achieves key negotiate by scalar multiplication other than using pairing computation which requires expensive computation cost. Moreover, we have adapted aggregate signature technique verifying the validity of transcripts simultaneously, which greatly improves the computational efficiency. We have proved the security of protocol under the intractability of DDH problem in the RO model.